Modern semiconductor electronic devices such as integrated circuit chips are formed by building multiple stacked layers of materials and components on a semiconductor substrate. The semiconductor devices typically incorporate numerous electrically active components which are formed on the substrate. Metal conductor interconnects, which may be made of copper in some embodiments, are formed by various additive patterning and deposition processes such as damascene and dual damascene to electrically couple the active components together by means of circuit paths or traces formed within one or more layers of dielectric material. Modern semiconductor fabrication entails a repetitive sequence of process steps including material deposition (conductive and non-conductive dielectric materials), photolithographic patterning of circuits in the dielectric material, and material removal such as etching and ashing which gradually build the stacked semiconductor device structures.
Chemical-mechanical polishing or planarization (“CMP”) is a technique used in semiconductor fabrication for planarization of the layers formed on the substrate in order to provide a uniform surface profile or topography upon which successive layers of materials may be built. As well known to those skilled in the art, CMP basically entails use of a polishing apparatus that is supplied with an abrasive chemical slurry which may contain an abrasive such as colloidal silicon dioxide or alumina, deionized water, and chemical solvents or oxidants such as hydrogen peroxide, potassium or ammonium hydroxide. The slurry is typically pumped under pressure to the CMP station by a slurry supply system and applied directly onto the surface of the semiconductor wafer. The slurry is then worked into the wafer surface by a rotating polisher pad or head to polish/plane the surface.
Slurries used for chemical-mechanical planarization may be divided into three categories including silicon planarization slurries, dielectric polish slurries and metals polish slurries. A silicon polish slurry is designed to polish and planarize poly silicon layers. The silicon polish slurry can include a proportion of particles in a slurry typically with a range from 1-15 percent by weight. An oxide polish slurry may be utilized for polishing and planarization of a dielectric layer formed upon a semiconductor wafer. Oxide polish slurries typically have a proportion of particles in the slurry within a range of 1-15 percent by weight. Conductive layers upon a semiconductor wafer may be polished and planarized using chemical-mechanical polishing and a metals polish slurry. A proportion of particles in a metals polish slurry may be within a range of 1-5 percent by weight.
Many slurry compositions are blended slurries that comprise a mixture of raw or concentrated slurry comprising slurry particles, water and at least one chemical component. Examples of raw slurries (that may also be referred to as concentrated slurries), include fumed and colloidal silica, alumina, and ceria. Examples of chemical components that may be used in CMP slurries include acids, bases, surfactants, and oxidizers or mixtures thereof. Many of the blended slurries which comprises raw slurry and/or water and/or one or more chemical components do not have a long shelf life and once they are combined may begin to deteriorate within a few hours if not used; therefore, necessitating the combination of the components of a blended slurry near the tool and once combined, the use of the blended slurry in less than 24 or fewer hours.
A slurry is a colloid, a suspension of particles in liquid. The suspension of the particles in a liquid can be detrimentally impacted by the components added to a raw slurry, particularly the chemical components and the manner and order of the additions of the components making up a blended slurry. The slurry must also be kept in motion to keep the particles dispersed in the liquid. Also, since the slurry deteriorates with time, it is important to check its characteristics and adjust them if necessary.
Additionally, the semiconductor and other industries require chemical blends for cleaning and surface preparation that do not contain slurry particles, but require blending a short time prior to use and movement of the chemical blend to mix and optionally keep the chemical blend homogeneous.
Electronic fabs continue to increase in size and output of semiconductor components. Apparatuses that can supply relatively large amounts and/or consistently blended slurries and/or chemical blends are needed.